This invention generally relates to a water-saving dual flush toilet system. More specifically, this invention relates to the efficient use of water in the holding tank of the toilet to selectively flush fluid or solid human wastes into sewers, septic tanks, or other sewage treatment system.
Water is in short supply in many places around the world. As population grows, the water usage increases accordingly. In the past numerous efforts have been made to conserve water usage including efforts to reduce the amount of water to flush toilets. Some of the inventions employ devices with two discharge openings: one is located above the other to use different volumes of water in the toilet tank to flush solid waste or liquid waste in the toilet bowl. Such approach has disadvantages. During the flushing as the water level lowers to the bottom of the toilet water tank the water pressure becomes lower. With lower water pressure, the flushing of the wastes can be less effective. Hence, either a large volume of water is needed to complete the flushing or multiple flushes are required to achieve satisfactory flushing results. As a result, excessive amount of water is consumed to flush the toilet.
To solve this problem, a dual flushing toilet system has been invented with selectively activating the toilet flushing mechanism to consume proper volume of water to flush the solid waste or the liquid waste while maintaining a highest possible water pressure during the flush operation. The water level in the toilet water tank stays above the discharge opening before the flush valve drops down and seals the discharge opening of the dual flush toilet. To flush the solid waste, a regular volume of water is used; to flush the liquid waste, a smaller volume of water is used.
At present two types of flush valves are widely used in various toilet systems. One type of flush valve is a plunger-shaped valve with a floating chamber at the bottom and a tubular portion on the upper portion of the flush valve. The tubular potion acts as an overflow pipe to drain the water into the toilet in case the inlet valve malfunctions. The bottom flange of the flush valve is seated against the discharge opening. This type of flush valve integrates the float chamber and the overflow pipe into one unit. It can generally slidably move upwardly and downwardly with the guidance of a spud secured on the discharge opening of the toilet water tank. A flush lever is used to activate the valve to move upwardly to open the discharge opening. When the flush valve is in the open position, the water in the toilet tank is discharged into the toilet bowl to flush the waste. As the level of the water in the tank lowers, the bottom of the flush valve becomes closer to the discharge opening and the buoyancy from the chamber of the flush valve becomes less. Hence, when the weight of the flush valve becomes greater than the buoyancy of the chamber of the flush valve, the flush valve drops down and closes the discharge opening. As the water inside the water tank drops, a float inside the water tank activates a water inlet valve to permit the water to flow into the toilet tank and refill the water. When the water level inside the water tank reaches the predetermined level, the float deactivates the water inlet valve to shut the water off.
Another type of flush valve has a generally hemisphere-shaped flapper valve body with a chamber in the lower portion. The flapper valve can pivotally rotate about a horizontal axis of a frame mounted primarily on the bottom portion of a vertical overflow pipe. A flush lever controls the hemisphere-shaped flush valve. The flush lever lifts the flush valve up, opens the water discharge opening, and permits the water from the toilet tank to flow into the toilet bowl to flush the wastes. The flush valve closes when the gravity of the valve is greater than the buoyancy of the flapper valve as the water level in the water tank lowers. The refill process is the same as the one described above.
It is generally recognized that vast majority of the dual action water saving toilet devices are developed around the hemisphere-shaped flush valves that employ two discharge openings. The volumes of water discharged through these two discharge openings are different because the two discharge openings are located at different elevations inside the toilet tank. However, there are three major disadvantages of these devices. First, each discharge opening permits the water above the discharge opening to be discharge into the toilet bowl. For different sizes of the toilet tank, their surface areas are different. This makes the volume of water consumed vary greatly. Second, dual flush toilets require a user to push, hold, and then release the flush handle. This operation requirement is inconvenient to the user. It is very difficult to control the timing to hold the flush handle. If the user holds the lever handle too long, excessive amount of water is used to flush the toilet; if the user releases the lever handle too soon, insufficient amount of water is used to flush the waste. As a result, multiple flushes may occur. Third, some of the mechanisms employed to control the dual flush operations are so complicated that they are expensive to manufacture, difficult to install, and inflexible to accommodate the various toilet tanks to achieve effective flushing results.
Very few efforts have been made for a dual flush toilet for the plunger-shaped flush valve toilet system in which the overflow pipe and the float chamber are integrated as one unit, because it is more difficult to develop a device to perform the dual flush functions than the hemisphere-shaped flash valve.
U.S. Pat. No. 6,317,899 to Brewer discloses a dual flush water conservation toilet including separate filling tanks in the toilet. A user can selectively empty different tanks to flush the solid or liquid waste. However, such approach to empting the whole tank of water cannot employ the water pressure to flush the waste effectively. It is also complex to manufacture and difficult to make adjustments.
One approach to achieving selective flushing is to place two separate flushing valves and on two discharge openings at different elevations. U.S. Pat. No. 4,069,591 to Awis, U.S. Pat. No. 4,172,299 to Pozo, U.S. Pat. No. 4,175,295 to Cameron, U.S. Pat. No. 4,504,984 to Burns, U.S. Pat. No. 5,042,096 to Bolli, U.S. Pat. No. 5,067,180 to Figeroid, U.S. Pat. No. 5,887,292 to Goren, U.S. Pat. No. 5,813,059 to Wang, U.S. Pat. No. 6,041,452 to Hsiao, and U.S. Pat. No. 6,571,400 to Reid, primarily employ two discharge openings in the water tank. Different activating mechanisms are employed to activate each valve to control the volume of water discharging through the discharge opening into the toilet bowl to flush the waste. Each invention uses a different activating mechanism to control the flash valves. However, all the inventions have some disadvantages. First, they are too complicated to manufacture. Second, water pressure drops down to almost zero when the water level lowers to the discharge openings. The lower water pressure makes the toilet flushing less effective.
Another type of invention for the dual flush toilet requires a user to hold the lever handle to control the amount of water used to flush the waste.
U.S. Pat. No. 4,837,867 to Miller shows a dual toilet flush system. This system employs one flap valve to control the volume of water to be used to flush the toilet. However, the user must hold the handle to keep the flush valve partially open to determine the time to flush the toilet. This operation requires that the user determine the flushing time, which makes it difficult to control the proper volume of water to flush the waste. It is also inconvenient for a user to hold the lever handle.
U.S. Pat. No. 5,073,995 to Jennison discloses a water saving device for flushing tank including a floating body mounted on a standpipe of the tank. The floating body can move upwardly or downwardly to forcibly contact the flushing valve. The weight of the floating body can be adjusted. This device can close the flushing valve before the water level reach the point that the gravity of the valve is greater than the buoyancy from the water to cause the valve to close down. However, there is no function to selectively control the water level. With the variations of the toilet tanks, such device cannot be adjusted to fit different toilet tanks.
U.S. Pat. No. 5,105,480 to Howell discloses a device that a pivoting cup is mounted on the toilet flap valve. Two flexible actuating elements control the position of the cup. A full flush or a partial flush can be achieved by controlling the orientation of a cup above the flush valve. However, the device is complicated and the pivoting cap is an extra element. Various factors such as precisely maintaining the positions of the parts can affect the functionality of the device.
U.S. Pat. No. 5,129,110 to Richter uses one flushing valve to achieve the selectable flushing function. This device needs a user to hold the flushing lever handle to control the time of flushing. Such operation varies greatly from different users. If a user cannot properly control the timing, either excessive water is used to flush the waste or insufficient water is discharged into the toilet bowl. In the later case, a second flush may be needed to obtain a satisfactory flushing result.
U.S. Pat. No. 5,191,662 to Sharrow discloses a device that is similar to U.S. Pat. No. 5,129,110. It also requires a user to hold down the flush handle to control the amount of water to flush.
U.S. Pat. No. 5,289,594 to Wiewiorowski discloses a toilet flush control system. This toilet flush control system provides a control over the volume of water used in conventional tank toilets. The disclosed toilet flush control apparatus and method can be used in existing toilets by easily retrofitting such toilets with said apparatus. The toilet flush control apparatus may also be incorporated into the design of new toilets. The apparatus comprises a flapper-type flush valve which by itself does not have adequate buoyancy to remain open during the flush cycle of a toilet and which is equipped with an eyelet member; a buoyant member capable of imparting the needed buoyancy to the valve during the flush cycle; a flexible line connected at one end to the buoyant member and passing through said eyelet, and mechanism for adjusting the vertical distance between the flush valve and the buoyant member from outside the toilet tank. The volume of water saved during flushing is equivalent to the volume of water between the level of the flush valve and the level of the buoyant member. However, this system cannot be easily operated and the buoyancy member can only be adjusted one at time. This toilet flushing system cannot selectively adjust the volume of water for flushing different wastes.
U.S. Pat. No. 5,319,809 to Testa shows a single valve dual module toilet flush system. However, this system needs a user to press the handle and hold and then release it to control the volume of water to be used. It is very difficult for a user to determine the duration of flushing the waste.
U.S. Pat. No. 5,855,025 to Williams discloses a single valve controlled toilet system. A water saver is inserted in place of a tube touted from the water inlet valve assembly to the overflow pipe. The pressured water is used to aid gravity to the valve in closing the flapper valve to seal the flush valve. However, the adjustment of the device is complicated and the adjustment is not convenient.
U.S. Pat. No. 5,996,135 to Hsieh discloses single valve controlled water saving toilet system. It employs a pull cord and a handle to control the volume of water used to flush the toilet. However, a user has to pull the cord to control the smaller amount of water to flush the toilet. The user has to decide how long to hold and release the pull cord. It is not convenient for a user to precisely control the proper amount of time to effectively complete the flushing task.
U.S. Pat. No. 5,031,254 to Rise discloses a toilet system to control the volume of water to flush the toilet. This toile flushing system employs a hollow valve with one opening at the bottom with a floating chamber to control the time for the valve to stay open. This system is complicated to manufacturing and difficult to assemble.
U.S. Pat. No. 5,966,749 to Goesling shows an adjustable toilet flush valve. This system has multiple holes on the Valve. The flush volume can be controlled by rotating the position of the valve to change the positions of the hole to control the time for the valve to stay open. However, this device does not have dual flush capability and cannot selectively to flush the different wastes once its position is set.
U.S. Pat. No. 6,151,724 to Klingenstein shows a single flap valve toilet system. It employs a floating ball to aid to close the valve before the water in the water tank drains to the bottom. This system does not have convenient adjusting functions to accommodate different toilet tanks.
U.S. Pat. No. 6,467,100 to Leach shows a water conservative toilet system that employs one single valve and a dual action handle to perform the flushing. Again, this system needs a user to determine when to release the handle. That requirement is inconvenient and can result in under flush if releasing the lever handle too soon or over flush if holding the lever handle too long.
U.S. Patent Publication No. US 2002/0133868 A1 to Comparetti shows a water-saving flap valve. It has a bleeder valve in the system. This system can perform a partial flush by tapping the flush handle. The disadvantage for this toilet system is that it is more difficult to control how long a user has to hold the flush handle.
U.S. Patent Publication No. US 2002/0157177 A1 to Sakura discloses a water-saving toilet flushing system. This system uses two tanks and two flap valves flushing system to control the volume of water. This system is expensive to manufacture. It is difficult to retrofit to existing toilet tank.
U.S. Patent Publication No. US 2003/0110555A1 to Tate discloses a dual action toilet flush mechanism. This toilet system has a drain shutter adapted for enabling and disabling the draining device; a water level sensor providing a shutter closer adapted for closing the drain shutter at a selectively adjustable low water level; a device for disabling water filing at a selected high water level; and a lever and chain arrangement for opening the drain shutter thereby enabling draining of the tank. That mechanism needs an operator to hold the flush lever to perform a full flush cycle, which is not convenient to operate. It is also complicated to enable and disable the draining device.
U.S. Patent Publication No. US 2001/0042265 to Han discloses a dual action toilet flush mechanism that can perform the dual flush operations. However, this system is extremely complex. It is expensive to manufacture and difficult to function properly.
U.S. Patent Publication No. US 2002/0148037 to Bellmore, US 2003/0014810 to Jarosinski, and US 2003/0028958 to Hand, and US 2003/0074727 to Hand, disclose a type of dual action toilet flush mechanism that can perform the dual flush operations. This system uses two flush handles and two discharge openings. They also have the low water pressure problem and inflexible to adapt to different toilet tanks.
German Patent No. DE315621 and DE3153688 to Hubatka Alex show a dual flush toilet system. However, this system is complex and expensive to manufacturer and install.
In summary, the previous inventions of the dual flush toilet system employ complicated mechanisms resulting in high cost of manufacturing of the components, difficult to install, or inflexible to retrofit existing toilets. Another major disadvantage of the prior inventions is that the selective flushing system requires a user to hold the flush handle to complete a flushing cycle. Such requirement can result in over flushing or under flushing, which leads to consuming more water. As a result, more water is used because of such ineffectiveness.